diff --git a/lib/fog/aws/auto_scaling.rb b/lib/fog/aws/auto_scaling.rb
index 1385f80af..314e1d468 100644
--- a/lib/fog/aws/auto_scaling.rb
+++ b/lib/fog/aws/auto_scaling.rb
@@ -35,6 +35,8 @@ module Fog
       request :describe_tags
       request :describe_termination_policy_types
       request :detach_load_balancers
+      request :detach_instances
+      request :attach_instances
       request :disable_metrics_collection
       request :enable_metrics_collection
       request :execute_policy
diff --git a/lib/fog/aws/models/auto_scaling/group.rb b/lib/fog/aws/models/auto_scaling/group.rb
index 3ca94f206..547893975 100644
--- a/lib/fog/aws/models/auto_scaling/group.rb
+++ b/lib/fog/aws/models/auto_scaling/group.rb
@@ -61,6 +61,18 @@ module Fog
           reload
         end
 
+        def detach_instances(*instance_ids)
+          requires :id
+          service.detach_instances(id, 'InstanceIds' => instance_ids)
+          reload
+        end
+
+        def attach_instances(*instance_ids)
+          requires :id
+          service.attach_instances(id, 'InstanceIds' => instance_ids)
+          reload
+        end
+
         def disable_metrics_collection(metrics = {})
           requires :id
           service.disable_metrics_collection(id, 'Metrics' => metrics)
diff --git a/lib/fog/aws/requests/auto_scaling/attach_instances.rb b/lib/fog/aws/requests/auto_scaling/attach_instances.rb
new file mode 100644
index 000000000..3fcf9498b
--- /dev/null
+++ b/lib/fog/aws/requests/auto_scaling/attach_instances.rb
@@ -0,0 +1,59 @@
+module Fog
+  module AWS
+    class AutoScaling
+      class Real
+        require 'fog/aws/parsers/auto_scaling/basic'
+
+        # Removes one or more instances from the specified Auto Scaling group.
+        #
+        #  cli equiv:
+        # `aws autoscaling attach-instances --instance-ids i-93633f9b --auto-scaling-group-name my-auto-scaling-group`
+        #
+        # ==== Parameters
+        #
+        #   * AutoScalingGroupName<~String> - The name of the Auto Scaling group``
+        #   * 'InstanceIds'<~Array> - The list of Auto Scaling instances to detach.
+        #
+        # ==== See Also
+        #
+        # http://docs.aws.amazon.com/cli/latest/reference/autoscaling/attach-instances.html
+
+        ExpectedOptions[:asg_name] = %w[AutoScalingGroupName]
+
+        def attach_instances(auto_scaling_group_name, options = {})
+
+          if instance_ids = options.delete('InstanceIds')
+            options.merge!(AWS.indexed_param('InstanceIds.member.%d', [*instance_ids]))
+          end
+
+          request({
+            'Action'               => 'AttachInstances',
+            'AutoScalingGroupName' => auto_scaling_group_name,
+            :parser                => Fog::Parsers::AWS::AutoScaling::Basic.new
+          }.merge!(options))
+        end
+      end
+
+      class Mock
+        def attach_instances(auto_scaling_group_name, options = {})
+          unexpected_options = options.keys - ExpectedOptions[:asg_name]
+
+          unless unexpected_options.empty?
+            raise Fog::AWS::AutoScaling::ValidationError.new("Options #{unexpected_options.join(',')} should not be included in request")
+          end
+
+          unless self.data[:auto_scaling_groups].key?(auto_scaling_group_name)
+            raise Fog::AWS::AutoScaling::ValidationError.new('AutoScalingGroup name not found - null')
+          end
+
+          response = Excon::Response.new
+          response.status = 200
+          response.body = {
+            'ResponseMetadata' => { 'RequestId' => Fog::AWS::Mock.request_id }
+          }
+          response
+        end
+      end
+    end
+  end
+end
diff --git a/lib/fog/aws/requests/auto_scaling/detach_instances.rb b/lib/fog/aws/requests/auto_scaling/detach_instances.rb
new file mode 100644
index 000000000..a021c5eac
--- /dev/null
+++ b/lib/fog/aws/requests/auto_scaling/detach_instances.rb
@@ -0,0 +1,69 @@
+module Fog
+  module AWS
+    class AutoScaling
+      class Real
+        require 'fog/aws/parsers/auto_scaling/basic'
+
+        # Removes one or more instances from the specified Auto Scaling group.
+        #
+        #  cli equiv:
+        # `aws autoscaling detach-instances --instance-ids i-2a2d8978 --auto-scaling-group-name my-asg --should-decrement-desired-capacity`
+        #
+        # ==== Parameters
+        #
+        #   * AutoScalingGroupName<~String> - The name of the Auto Scaling group``
+        #   * 'InstanceIds'<~Array> - The list of Auto Scaling instances to detach.
+        #
+        # * options<~Hash>:
+        # 'shouldDecrementDesiredCapacity'<~Boolean> - decrement the asg capacity or not (it will boot another if an instance id detached)
+        #
+        # ==== See Also
+        # http://docs.aws.amazon.com/AutoScaling/latest/DeveloperGuide/detach-instance-asg.html
+        #
+
+        ExpectedOptions[:asg_name] = %w[AutoScalingGroupName]
+        ExpectedOptions[:instance_ids] = %w[AutoScalingGroupName]
+
+        def detach_instances(auto_scaling_group_name, options = {})
+
+          if should_decrement_desired_capacity = options.delete('ShouldDecrementDesiredCapacity')
+            options.merge!('ShouldDecrementDesiredCapacity' => true.to_s)
+          else
+            options.merge!('ShouldDecrementDesiredCapacity' => false.to_s)
+          end
+
+          if instance_ids = options.delete('InstanceIds')
+            options.merge!(AWS.indexed_param('InstanceIds.member.%d', [*instance_ids]))
+          end
+
+          request({
+            'Action'               => 'DetachInstances',
+            'AutoScalingGroupName' => auto_scaling_group_name,
+            :parser                => Fog::Parsers::AWS::AutoScaling::Basic.new
+          }.merge!(options))
+        end
+      end
+
+      class Mock
+        def detach_instances(auto_scaling_group_name, options = {})
+          unexpected_options = options.keys - ExpectedOptions[:asg_name] - ExpectedOptions[:instance_ids]
+
+          unless unexpected_options.empty?
+            raise Fog::AWS::AutoScaling::ValidationError.new("Options #{unexpected_options.join(',')} should not be included in request")
+          end
+
+          unless self.data[:auto_scaling_groups].key?(auto_scaling_group_name)
+            raise Fog::AWS::AutoScaling::ValidationError.new('AutoScalingGroup name not found - null')
+          end
+
+          response = Excon::Response.new
+          response.status = 200
+          response.body = {
+            'ResponseMetadata' => { 'RequestId' => Fog::AWS::Mock.request_id }
+          }
+          response
+        end
+      end
+    end
+  end
+end
diff --git a/tests/requests/auto_scaling/auto_scaling_tests.rb b/tests/requests/auto_scaling/auto_scaling_tests.rb
index f3998392c..a7743959e 100644
--- a/tests/requests/auto_scaling/auto_scaling_tests.rb
+++ b/tests/requests/auto_scaling/auto_scaling_tests.rb
@@ -35,7 +35,15 @@ Shindo.tests('AWS::AutoScaling | auto_scaling_tests', ['aws', 'auto_scaling']) d
       Fog::AWS[:auto_scaling].detach_load_balancers(@asg_name, 'LoadBalancerNames' => 'elb-test-fog').body
     end
 
-    tests("#describe_auto_scaling_groups").formats(AWS::AutoScaling::Formats::DESCRIBE_AUTO_SCALING_GROUPS) do
+    tests("#detach_instances").formats(AWS::AutoScaling::Formats::BASIC) do
+      Fog::AWS[:auto_scaling].detach_instances(@asg_name, 'InstanceIds' => 'i-deadbeef').body
+    end
+
+    tests("#attach_instances").formats(AWS::AutoScaling::Formats::BASIC) do
+      Fog::AWS[:auto_scaling].attach_instances(@asg_name, 'InstanceIds' => 'i-deadbeef').body
+    end
+
+   tests("#describe_auto_scaling_groups").formats(AWS::AutoScaling::Formats::DESCRIBE_AUTO_SCALING_GROUPS) do
       Fog::AWS[:auto_scaling].describe_auto_scaling_groups().body
     end
     tests("#describe_auto_scaling_groups").formats(AWS::AutoScaling::Formats::DESCRIBE_AUTO_SCALING_GROUPS) do